Field of the Invention
The present invention relates to wireless charging, and more particularly, to a contactless power reception device.
Related Art
In recent years, supply of portable electronic devices including a smart phone, a laptop, an MPEG-1 audio layer (MP3) player, a headset, and the like has been spread. However, since the portable electronic devices operate by consuming power stored in battery cells (e.g., a primary cell, a secondary cell, and the like), the battery cell needs to be charged or replaced in order to continuously operate the portable electronic devices.
A method of charging the battery cell is generally divided into a contact type charging method of charging the battery cell by using a power supply line and a power supply terminal and a contactless charging method of charging the battery cell with wireless power induced by a magnetic field generated from a primary coil of a wireless power transmitting apparatus by using a wireless power reception device. However, in the contact type charging method, an instant discharge phenomenon occurs as different potential differences are generated at both terminals when a charger and a battery are coupled to or separated from each other and the power supply terminal is exposed to the outside, and as a result, fire may occur when foreign materials are accumulated in the power supply terminal and the battery is naturally discharged and the life-span and the performance of the battery deteriorate due to moisture. Accordingly, in recent years, in order to solve the problems, a research into the contactless charging method has been in active progress.
As one of technologies associated with the contactless charging method, “Contactless Charging System” of Korean Patent Registration No. 10-0971705 discloses that a wireless power signal is transmitted by determining measuring a delay time up to a time of receiving a response signal corresponding to a request signal from a time of outputting the request signal through a primary-side core unit and comparing the measured delay time with a reference stand-by time when a load change is sensed in the primary-side core unit of a contactless power transmission device and thereafter, determining that a corresponding object is a foreign material when the measured time is shorter than the reference stand-by time and determining that the corresponding object is a normal contactless power reception device when the measured time is longer than the reference stand-by time.
In the magnetic induction type contactless charging system, the wireless power reception device generally communicates with the wireless power transmission device by an amplitude-shift keying (ASK) modulation method. In detail, when the amplitude of the wireless power signal which the wireless power reception device receives from the wireless power transmission device is modulated, the modulated signal is induced to a transmitting coil of the wireless power transmission device. The wireless power transmission device performs communication by detecting the modulated signal induced to the transmitting coil. However, in the contactless charging system, as the intensity of the wireless power signal transmitted from the wireless power transmitting apparatus increases, distortion occurs in the modulated signal and this causes a communication error between the wireless power transmitting apparatus and the wireless power receiving apparatus.